The Golgi receives new proteins and lipids from the ER, finishes them up, addresses them and sends them to their final destination. In this way, the Golgi could be the postal service of the city. Lysosomes get rid of unusable waste within the cell and recycles those materials that can be reused, making it the recycling and garbage center of the city. Mitochondria are where ATP, the main energy molecule, is made. It could be considered the city's power plant. Then we have the cell's cytoskeleton, which gives the cell its shape, strength and its ability to move. It can be looked at as the roadways and bridges of the city. ("Chemical Composition of the Body," 2005) Cells do not act alone and have help from things like enzymes to complete their job. Enzymes are proteins make chemical reactions within cells occur faster ("Chemical Composition of the Body," 2005). Without enzymes, most reactions would not occur under the conditions of the temperatures and pressures compatible with life ("Chemical Composition of the Body," 2005). Respiration and photosynthesis both occur within living organisms and are different reactions, but they complement one another. Respiration occurs when there is an inhalation and an exhalation ("Chemical Composition of the Body," 2005). Photosynthesis is the process where plants, algae and photosynthetic bacteria use energy from light to synthesize organic compounds and results in the release of molecular oxygen (Whitmarsh and Govindjee, 1995). Both respiration and photosynthesis take something from the external environment, bring it into the living organism and then release it back out into the external environment.

One...

Disaccharides form when two monosaccharides are chemically bonded together. Peptides are formed when monomers from amino acids join. Both of these occur through the chemical reaction of condensation and both have the common by-product of water as a result. (Farabee, 2010b)
In conclusion, living organisms have some basic, common characteristics; but that does not make them any less complex or different from one another. The cells within a living organism alone show their complexity. The way the atom can change so drastically with just the addition or subtraction of protons, neutrons or electrons; the structure of a cell; the help that cells receive from such things as enzymes; and chemical reactions that occur within cells such as condensation all show the complexity of the living organism.

WORKS CITED

Biology-Online. (2005, May 15) "Chemical composition of the body." Retrieved December 2, 2011 from www.biology-online.org/9/1_chemical_composition.htm.

Farabee, M.J. (2010a, May 18) Online Biology Book. "Introduction: The nature of science and biology." Retrieved December 1, 2011 from www.emc.maricopa.edu/faculty/farabee/biobk/biobookintro.html .

(2010b, May 18) Online Biology Book. "Chemistry II: Water and organic materials." Retrieved December 2, 2011 from www2.estrellamountain.edu/faculty/farabee/biobk/biobookchem2.html .

Whitmarsh, John and Govindjee. (1995) "Photosynthesis." Encyclopedia of Applied Physics.(Vol. 13): 513-532. VCH Publishers, Inc.